var arr = [1, 2, 3, 2, 3, 4]
var res = arr.sort()
console.log(res);

~function () {
    function check(n) {
        n = Number(n)
        return isNaN(n) ? 0 : n
    }
    function add(n) {
        n = check(n)
        return this + n
    }
    function minus(n) {
        n = check(n)
        return this - n
    }
    Number.prototype.add = add
    Number.prototype.minus = minus
}()
console.log((5).add(2).minus(3));